Fix building relative URIs
Examples:
testURI --relative --base file:///a file:///b
- New correct result:
b
- Old incorrect result:
../b
testURI --relative --base file:///a file:///
- New correct result:
./
- Old incorrect result:
../
testURI --relative --base file:///a/b file:///a/
- New correct result:
./
- Old incorrect result:
../../a/
This bug affects an Inkscape merge request.
This MR also adds the <code data-sourcepos="17:25-17:34">--relative</code> flag to <code data-sourcepos="17:46-17:52">testURI</code> and removes some unreachable code.